In the Town of Beginnings of SAO, there existed a hidden underground dungeon.
This area was never meant to be accessible during the normal course of gameplay.
Within this region, there were a series of monsters that had been scrapped during SAO's development.
As well as a special boss in the form of a grim reaper—its stats all adjusted to the absolute upper limit for monsters, used as a comparison template.
At the very end of this area stood a lower-tier system control console for SAO.
In other words, an admin console.
This sub-console's main purpose was to monitor the mental state of all SAO players.
The AI administrator was supposed to adjust players' mental states in real time.
When a player's mental state became too low, it would provide encouragement, guidance, and comfort.
If a player's mental state dropped below the safety threshold, it would forcibly log the player out and monitor their physical indicators—
In order to issue an alert or dial emergency services if necessary.
This was a required module to get full-dive games approved for release.
But what Akihiko Kayaba wanted to create wasn't a normal game at all—
It was a real death game.
Even if a player's mental state collapsed, the forced logout protocol would never activate.
Thus, this sub-console and its AI administrator became "useless."
The AI administrator would still attempt to fulfill its programmed duties—but once blocked by higher-tier permissions, it would fall into a logical contradiction and eventually crash.
Because of that, this sub-console's dungeon area only entered the normal game world due to a bug.
And it was also the only place Haruto could think of where system access might be obtained.
After some searching—Haruto and the other two found a previously undiscovered underground entrance in the wilds near the Town of Beginnings.
"…Is this a hidden dungeon? There's been no intel about it at all. Could it be one of those areas that opens only as the game progresses?"
Argo looked at the eerie entrance with suspicion.
Asuna, however, nervously clutched Haruto's hand.
She wasn't afraid of normal monsters—
But the ominous aura of this mysterious place and whatever unknowns might lurk within—
They unnerved the girl deeply.
Haruto gently comforted Asuna, then stepped inside.
After descending a long staircase—
They arrived at a simple maze.
There were no environmental decorations—just stone blocks.
Argo lit a torch for illumination.
But they had barely taken a few steps when a flash of blue light flared ahead.
A monster had spawned.
It was a type of giant toad they'd never seen before. Asuna shivered, then immediately drew her rapier. In a flash, her blade danced brilliantly.
With a flurry of strikes, the toads shattered into data fragments and vanished.
A results screen popped up.
Seeing those disgusting monsters wiped out, Asuna finally relaxed.
But Argo was already scrutinizing the result window.
"…Strange. There's no 'defeated target' message, no EXP gained, and the only drop item is food...?"
As an information broker, Argo had a keen nose for oddities.
She instantly sensed something off.
This hidden dungeon clearly wasn't normal.
And when Asuna heard the word "food," her face turned pale.
She was a talented cook, but using something like toad meat as an ingredient?
She'd rather die.
As the trio pressed deeper—
More monsters appeared.
All of them unknown types with no names displayed, and only food as drops.
And rather than a dungeon, the place looked more like a hollow hall. There were no branching paths—it felt like a long, narrow box with zero design effort.
"This doesn't look like a game area at all—it's more like a testing area."
Argo voiced the truth.
Just then, something unusual came into view up ahead.
There was a region encased in crystal, glowing with a special light.
As Argo started to rush toward it out of curiosity—
Haruto grabbed the back of her collar and pulled her back.
"Careful."
Their journey here had been suspiciously smooth.
After all, most of the scrapped monsters were from mid-to-lower floors. Upper-floor monsters often had background stories and were rarely scrapped.
Given their levels, the trio had been steamrolling everything.
But this part… was different.
Just as Haruto pulled Argo back—
A jet-black flame ignited in mid-air.
A giant black scythe descended from the sky, crashing down toward the three of them.
Fortunately, Haruto's warning had the others on alert—they jumped clear just in time. In the next moment, a massive humanoid figure emerged from the flames.
Its appearance bore a striking resemblance to the avatar Akihiko Kayaba used during the opening speech in the town square.
Both wore black robes—but this one had a skull for a head, not a hooded cloak.
As it gripped the scythe, the signature massive boss health bars appeared in the air.
Seeing the monster, Asuna and Argo immediately felt a wave of PTSD.
Kayaba had traumatized the players too thoroughly.
Haruto, however, calmly drew his longsword and prepared for battle.
Though this grim reaper boss had all its attributes set to the maximum limit for monsters—
Haruto was now at max level too.
Statistically, it wasn't an impossible fight.
Asuna and Argo both went into full alert mode.
Especially Argo, whose body had gone completely tense.
She was closest to the boss.
Under normal conditions, the boss would aggro the nearest player without any aggro output.
But the grim reaper boss raised its scythe and swung directly at Haruto.
"Special aggro mechanic?!"
Argo gasped, rushing to assist.
But Haruto casually sidestepped the swing, then leapt onto the scythe itself.
"Did Kayaba leave his code research here?"
From the way the grim reaper moved, Haruto could tell—it had signs of artificial AI. It was able to assess the most threatening player nearby. Not just by stats, but through more human-like evaluation.
Before SAO launched, Shiro had given Akihiko Kayaba a bit of AI code.
He hadn't expected the guy to use it on a test-area boss.
While thinking, Haruto had already slashed several times—his sword strikes landing on the reaper's scythe-wielding arm.
Crimson data fragments scattered.
The boss's health visibly dropped.
Enraged by the attack—
The reaper boss swept its scythe horizontally at Haruto.
Asuna and Argo gasped at the sight.
In normal gameplay, players suffered stiff delays after attacking.
But Haruto spun like a swallow in mid-air, dodging effortlessly and even slashing twice more.
His fluid movements were a visual spectacle.
Relieved, Asuna and Argo began attacking as well.
With Haruto's flawless technique—
The reaper boss's health dropped in large chunks.
The speed of the battle was shocking.
When Haruto landed another full Eclipse combo—the highest-level single-handed sword skill—
He glanced toward the crystal not far away.
And caught a glimpse of a black-and-white figure behind the crystal.
It vanished in an instant.
But with Haruto's vision, he was certain it wasn't a hallucination.
Kayaba? No, that guy probably didn't notice this bugged area.
Something outside the plot? Then where did it come from?
Questions surfaced in his mind.
Haruto's attacks grew even faster.
The reaper's stacked health bars rapidly shrank to the final layer.
Normally, bosses would enter berserk mode when at low health.
But as a stat comparison template, this reaper boss had no such design.
In fact, it was easier to kill than most bosses. With its HP depleted, the massive figure shattered into data fragments.
Unfortunately, it dropped no items.
But Haruto ignored that and strode directly toward the crystal zone. He was more curious about that mysterious figure he had just seen.
And just as Haruto approached—
Suddenly, the entire hidden dungeon—the walls, floor, and even the crystal—
Lit up with blood-red warning prompts.
Like fresh blood—intense and glaring.
At the same time, Haruto felt his digital body freeze—unable to move.
Looking to the side, Argo and Asuna were clearly in the same state.
And just then—
The black-and-white figure flickered into view once again.